Control mechanism for oven burners



C. M. MAYER ET AL CONTROL MECHANISM FOR OVEN BURNERS May 5, 1953 2 SHEETSSHEET 1 Filed Dec. 10, 1951 INVENTORS Char/es M. Mayer BY 9.]0/1/1 M. Hoff fifty Patented May 5, 1953 CONTROL MECHANISM FOR OVEN BURNERS Charles M. Mayer and John M. Hoff, Mansfield, Ohio, assignors to The Tappan Stove Company, Mansfield, Ohio, a corporation of Ohio Application December 10, 1951, Serial No. 260,904

1 Claim. 1

This invention relates to a control mechanism for cooking range burners using gaseous fuel and is a modification of the control mechanism shown in our co-pending application filed April 3, 1950, Serial No. 153,664, now Patent No. 2,577,787. It is especially designed and adapted for controlling the operation of oven burners in cooking ranges, and may be used in conjuction with a time control mechanism or independently thereof as desired.

The mechanism is designed for use with a main gaseous fuel burner which is adapted to be ignited by a constantly burning gaseous fuel pilot burner. As long as the pilot burner is ignited it is immaterial whether or not the main burner burns constantly during operation. It may be extinguished for some reason, but it will be promptly re-ignited by the pilot burner if fuel is supplied thereto. But if the pilot burner is eX- tinguished for any reason during operation a very dangerous situation sometimes arises. Let us assume that both the pilot burner and the main burner are extinguished during operation for some reason. Gas can then flow to the main burner but since the pilot burner is extinguished the main burner will not be ignited and unburned gas will accumulate in the oven which may violently explode when an attempt is made to ignite either the main or pilot burner. It has been found by experience that both the pilot burner and the main burner are frequently extinguished during operation, This is sometimes due to a momentary failure of the gas supply or the slamming of the oven door or to various other reasons.

In order to prevent any accumulation of unburned gas and thus eliminate danger of an explosion therefrom in the event the pilot burner is extinguished for any reason during operation, we provide in our improved apparatus a safety control mechanism by which the supply of gas to the main burner is automatically cut off, in the event the pilot burner is extinguished for any reason during operation. The apparatus is so constructed and arranged that we also utilize this safety control mechanism to turn the gas on and off to initiate and terminate operation of the main burner and thereby eliminate the additional manually operable shut off valve generally used in burner control apparatus of this type.

Our improved apparatus includes a main gaseous fuel burner by which the oven in a cooking range is heated. The main burner is adapted to be ignited by a gaseous fuel pilot burner which burns both during operation and non-operation of the main burner. During periods of nonoperation the supply of gas to the main burner is cut off by the safety control mechanism which is interposed in a conduit between the gas supply manifold and the burners. During operation gas flows from the manifold into a safety control mechanism. From the safety control mechanism gas flows through the main conduit and a standard thermostatically operated oven temperature control valve to the main burner.

The safety control mechanism comprises a control valve which is yieldingly biased to closed position and an electromagnet which when energized is operative to hold the control valve in open position after it has been manually moved from closed to open position, but which is not strong enough to move the control valve fromclosed to open position. The electromagnet is energized by a multiple thermocouple which generates a minute current of the order of from 200 to 250 millivolts. To initiate operation the valve is manually moved from closed to open position and then released after which the electromagnet holds the valve in open position. Gas cannot flow from the manifold to the main burner where it is isnited by the pilot burner. The thermocouple, as long as it is heated by the pilot burner, maintains the safety control valve mechanism in open condition. The oven temperature control valve then regulates the supply of gas to the main burner so as to maintain the desired oven temperature. As long as the pilot burner is ignited the main burner will burn normally under the control of the oven temperature control valve. But if during operation the pilot burner is extinguished for any reason the thermocouple will immediately cool and de-energize the electromagnet which allows the safety control mechanism to automatically cut off the supply of gas to the main burner. As an example of the manner of operation of the apparatus, let us assume that during operation the pilot burner is suddenly extinguished. The thermocouple will then immediately cool, allowing the safety control mechanism to cut off the flow of gas from the manifold to the main burner. The pilot burner must then be manually re-ignited and, after the thermocouple has been re-heated, the control valve manually re-opened to re-initiate operation of the main burner.

In order to extinguish the main burner to terminate operation we provide an interrupter switch in the circuit between the thermocouple and the safety control valve mechanism. The interrupter switch is yieldingly biased to closed position and when momentarily opened breaks the circuit between the thermocouple and the safety control mechanism which de-energizes the electromagnet and releases the control valve allowing it to cut off the supply of gas to the main burner and thus terminate operation.

In order to adapt the apparatus for automatic control whereby operation of the main burner is automatically initiated at a predetermined set time and is automatically terminated at a predetermined set later time we inter-pose a normally open solenoid valve in the fuel supply conduit between the oven temperature control valve and the main burner and we provide a standard electrically operated time control mechanism which includes a normally open switch which we dispose in series with the solenoid for actuating the solenoid valve. When used the time control mechanism is set as desired which closes the time control switch and energizes the solenoid, thus closing the solenoid valve; and then the control valve is manually opened after which the electromagnet will hold the control valve in open position. Gas can now flow past the control valve and the oven temperature control valve, but it cannot yet flow to the main burner as the solenoid valve is now closed. At the set time the time control mechanism will open the time control switch which will ale-energize the solenoid and open the solenoid valve. Gas will now flow to the main burner and be ignited by the pilot burner, after which the main burner will operate as described in connection with manual control until its operation is terminated by the time control mechanism closing the time control switch at the set time. The closing of the time control switch will effect the closing of the solenoid valve and cut off the supply of gas to the main burner. The interrupter switch is then momentarily opened which effects the closing of the control valve, and the time control mechanism is re-set for manual operation.

Tlie'principal object of the invention is to provide a simplified control mechanism for gaseous'fuel cooking range oven burners which is op erative to cut off the supply of fuel to the burner in the event the pilot burner by which the oven burner is ignited is extinguished for any reason during operation.

Another object of the invention is to provide in an apparatus of the character described mechanism which acts as a safety control during operation of the oven burners and as a shut oil valve during periods of non-operation.

Another object of the invention is to utilize the thermocouple circuit in an apparatus of the character described for maintaining or terminating'operation of the burner.

Another object of the invention is to provide a control apparatus of the character described which may be used in conjunction with a time control mechanism or independently thereof as desired.

Other and more limited objects of the invention will be apparent from the following specification and the accompanying drawings forming a part thereof wherein:

Fig. l is a diagrammatic layout illustrating our improved control mechanism as applied to a cooking range oven burner using gaseous fuel;

Fig. 2 is an enlarged vertical section through the safety control mechanism showing it in closed position; and

Fig. 3 is a view similar to Fig. 2 showingthe safety control valve mechanism in open position.

Referring now to the drawings by reference characters, the numeral I indicates a gaseous fuel burner which is mounted in or in heating relation to a cooking range oven 2. Gaseous fuel is supplied to the burner I from a manifold M through a conduit 3. Interposed in the conduit 3 are a safety control mechanism generally indicated by the numeral 4, and an oven temperature control valve 5. During operation gas flows from the manifold M through the conduit to the safety control mechanism 4, to be described in detail hereinafter. From the safety control mechanism :5 the gas flows through the conduit 3 and the oven temperature control valve 5 to the burner l. The oven temperature control valve 5 is operative to regulate the amount 01' gas flowing to the burner l in order to maintain the oven at any desired set temperature. The valve 5 is set to any desired temperature by a handle I! having a pointer l2 which cooperates with a graduated dial l3 carried by the valve 5. The valve 5 is controlled according to the temperature setting by a thermostatic element M which is mounted in the oven 2 and is connected to the valve 5 as shown at l5. The oven temperature control valve 5 is of standard well known construction. Consequently it is not shown in detail herein. There are many different constructions available any one of which will work equally well herein. Gas is also supplied to a pilot burner it through a secondary conduit ii which extends between the manifold M and the pilot burner is. The pilot burner I6 is disposed adjacent the rear end of the main burner i in position to ignite the burner I when gas is supplied thereto. A multiple thermocouple 2t which is mounted in position to be heated by a flame from the pilot burner 15 is operative when heated to hold the safety control mechanism i open to supply gas to the main burner i, and when cold to release the safety control mechanism so that it automatically closes and cuts off the supply of fuel to'the burner I.

An electric circuit between the thermocouple 2G and the safety control valve mechanism 5 is established by a copper tube 26, which encloses an insulated Wire 21. The wire 2'! is severed between the thermocouple 2E! and the safety control mechanism 4 and an interrupter 28 having terminals 29 and 30 is interposed between the severed ends. One of the severed ends of the wire 21 is connected to the terminal 29 and the other severed end is connected to the terminal 30. A normally closed push button switch 6 is mounted in a casing 1 secured to a wall 8 of the cooking range. The'switch B, which is yieldingly biased to closed position by a spring I8, comprises the contacts l9 and 2| and the bar 22 to which a push button 23 is connected. The terminal 25 of the interrupter 28 is connected to the contact IQ of the switch 6 by the lead 24; and the terminal at of the interrupter 28 is'connected to the contact 2| of the switch 6 bythe lead 25. The purpose and function of the switch Y 5 will be described hereinafter.

The construction of the safety control mechanism 4 will now be described, reference being had to Figs. 2 and 3 of the drawing. This mechanism comprises a casing 35 having a chamber 36 in one end thereof and a chamber '31 in the having end walls 44 and 45, is carried by the cap 4| and extends into the chamber 36. A valve stem 46 which is slidably mounted in a bushing 41 carried by the end wall 45 of the sleeve 43, extends from the chamber 36 into the sleeve 43. A valve disc 48 of suitable material is secured to one end of the valve stem 46 within the chamber 36, and a metal disc 49 is secured to the other end of the stem 46 within the sleeve 43. A spring 55 disposed about the valve stem 46 between the valve disc 48 and the end wall 45 of the sleeve 43 normally holds the valve disc 48 against the valve seat 39. An electromagnet is secured to one end of a hollow exteriorly threaded stud 52 which extends out through aligned apertures in the end wall 44, of the sleeve 43, and in the end of the cap 4|. A nut 53 screwed onto the outer portion of the stud 52 securely holds the magnet 5| and the sleeve 43 in place. The legs of the magnet 5| have a winding 54 thereon one end of which is connected to the tube 26 and the other end of which is connected to the wire 21 in the tube 26. The tube 26 is inserted into the hollow stud 5'2 and is held in place by a screw fitting 52a. A sleeve 55 is screwed into a threaded recess in the end of the cap 42, as indicated at 56, and extends into the chamber 31 a slight distance. One end of the sleeve 55 is closed by an end wall 51, and the other end which is open registers with a circular aperture 56 in the end wall of the cap 42. A plunger 59 is slidably mounted in the sleeve 55 and extends out through the aperture 58 in the cap 42. A stem 62 which is secured to the inner end of the plunger 59 extends out through an aperture 63, in the end wall 51 of the sleeve 55, and through the chamber 31 and into the bore 38. A compression spring 61 is disposed about the stem 62 within the sleeve 55 between the inner face of the end wall 51 and the inner end of the plunger 59. The spring 61 is operative to return the plunger 59 and stem 62 from the position shown in Fig. 3 back to their normal position as shown in Fig. 2, after the plunger has been released. A port 68 in the casing 35 provides communication between the chamber 36 and the conduit 3 to allow gas to flow from the manifold M through the conduit 3 into the chamber 36. During operation of the main burner gas flows from the chamber 36 through the reduced intermediate bore 38 and into the chamber 31. A port 16 establishes communication between the chamber 31 and the conduit 3 to permit the flow of gas from the chamber 31 to the main burner I through the oven temperature control valve 5.

The operation of the apparatus under manual control will now be described. To initiate operation of the burner I it is only necessary to momentarily manually depress the plunger 59 and then release it. The depressing of the plunger 59 shifts the control valve mechanism from the position shown in Fig. 2 to the position shown in Fig. 3. As soon as the plunger 59 is released to spring 61 returns the plunger 59 and stem 62 back from the position shown in Fig. 3 to the position shown in Fig. 2, and the electromagnet, being constantly energized while the constantly burning pilot burner is ignited, retains the valve mechanism in the chamber 36 in the position shown in Fig. 3. Gas can then flow through the safety control mechanism 4 to the main burner where it is ignited by the pilot burner I6. To terminate operation of the burner it is only necessary to momentarily depress the push button 23 which opens the switch 6 and breaks the circuit between the thermocouple 28 and the winding 54 of the electromagnet 5|. The breaking of this circuit deenergizes the electromagnet 5| after which the spring 59 returns the valve mechanism in the chamber 5| back from the open position shown in Fig. 3 to the closed position shown in Fig. 2 which cuts off the supply of gas to the burner I and terminates operation thereof.

If during operation the pilot burner I6 is extinguished for any reason the thermocouple 20 will immediately cool which will de-energize the electromagnet 5| after which the spring 58 will shift the valve mechanism in the chamber 36 from open to closed position and cut oil the supply of fuel to the main burner I. To reinitiate operation after it has been terminated by the extinguishment of the pilot burner, the pilot burner I6 must be manually re-ignited and after the thermocouple 26 has been reheated the plunger 59 must be momentarily depressed after which the operation will be as previously described.

In order to adapt the apparatus for automatic control whereby operation of the main burner is automatically initiated at a predetermined set time and is automatically terminated at a predetermined set later time we interpose a normally open solenoid valve 15 in the conduit 3 between the oven temperature control valve 5 and the burner and we provide a standard electrically operated time control mechanism 16 which is adapted to open and close a switch 11 at predetermined set times. The switch 11 is mounted in series with a solenoid 18 which is operative when energized to maintain the normally open valve 15 closed.

When used the time control mechanism 16 is first set to initiate operation of the burner at a predetermined time and to terminate operation thereof at a predetermined later time. The setting of the time control 16 closes the normally open switch 11 which energizes the solenoid 18 which then closes the normally open valve 15. Then the plunger 59 of the safety control mechanism 4 is momentarily depressed which opens the control valve in the chamber 36. After the plunger 56 is released the electromagnet 5|, which is constantly energized while the constantly burning pilot burner |6 is ignited, retains the control valve in open position. Gas can now flow from the manifold M through the safety control mechanism 4 but cannot yet reach the burner I as the normally open valve 15 in the conduit 3 is now closed. At the set time the time control 16 opens the switch 11 which deenergizes the solenoid 18 and opens the valve 15. Gas will now flow to the burner I which is then ignited by the pilot burner l6. Under normal conditions the burner I will operate under the control of the oven temperature control valve 5 until at the set time the time control 16 again closes the switch 11 which energize the solenoid 18 and closes the valve 15 thus cutting off the supply of fuel to the burner and terminates operation thereof. The push button switch 6 is then momentarily manually opened which breaks the circuit between the thermocouple 20 and the electromagnet 5| and de-energizes the magnet 5|. The control valve in the chamber 36 is then closed by the spring 50. The time control 16 is then set for manual control which opens the switch 11 and de-energizes the solenoid 18 thus opening the valve 15. The apparatus is now ready for the next operation of the burner I.

If during automatic operation the pilot burner H is extinguished for any reason the safety-com trol mechanism 4 will cut off the supply of gas to the burner l as explained in connection with manual control.

From the foregoing it-will be apparent to those skilled in this art that We have provided a very simple and efficient apparatus for accomplishing the objects of the invention.

It is to be understood that we are not limited to the specific construction shown and described herein as various niodifieations may be made therein within the scope of the appended claim.

What is .claimed-isi In a control apparatus for a gaseous fuel oven burner the combination of a fuel supply manifold, a main burner, a .fuel supply conduit through which fuel is supplied to said burner from said manifold, a constantly burning pilot burner operative to ignite said main burner, a normally closed valve interposed in. said conduit between said. manifold and said main burner,

vmeans yieldingly biasing said valve to closed position, means by which said valve is manually moved to open position, a, thermocouple mounted ative when energized-to maintain said valve in open position after said valve has beenmanually moved to openposition, a thermocouple mounted in position to be heated-by saidpilot burner, an electric circuit between said thermocouple and said electromagnet through whichsaid electromagnet isenergizedby said thermocouple when said thermocouple is heated, and a normally closed switch in said electric circuit, said switch being operative when openedto break said circuit and de-energize said electromagnet, a normally open valve interposed in said conduit between said normally closed valve and said mainburner,

a solenoid operative when energized to maintain said normally open valve closed, a normally open switch by which the energization of said solenoid is controlled, a time control mechanism adapted to be manually set for either manual or automaticcontrol of said main burner, and operative connections between said time control mechanism and said normally open switch through which said normally open switch is opened and closed by said time'control mechanism, said time control mechanism being operative upon the setting thereof for automatic control of'said main burner to.close said normally open switch and at a predetermined later time to open said normally open switch and at a still later time to close said normally open switch and to again open said normally open switch upon the resetting of said time control mechanism for manual control of said main burner.

CHARLES M. MAYER. JOHN M. 'HOFF.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,353,042 Koch July 4, 1944 2,562,536 Mayer July,3l, 1951 

